Nomenclature

Species name :

Diplotaxis erucoides  (L.) DC.

Authority :

Carl von Linne, Sweden, 1707-1778 ;
Augustin Pyramus de Candolle, Switzerland, 1778-1841

Synonyms :

Plant Family :

Brassicaceae  Juss. (= Cruciferae )
(Mustard or Cress Family)

English name(s) :

White Wall Rocket, White Rocket

Maltese name(s) :

Ġarġir abjad

Status for Malta :

Indigenous. Present on the Maltese islands before man

Name Derivation :

Diplotaxis = ? unknown;
erucoides = looks like plants of the Genus Eruca (Latina)

Remarks :

-

Morphology and structure

Plant description and characters

Life Cycle:

Annual.

Growth Form:

THEROPHYTE (annuals)

Habitat:

Fields, waysides, traffic islands, places with plenty of soil.

Frequency:

Very Common

Localities in Malta:

Very Common throughout the countryside of the Maltese Islands especially in uncropped fields. Often seen in traffic islands in October-November.

Plant Height:

20-60cm.

Flowering Period:

Sep-Jun

Protection in Malta:

Not Protected by Law (LN200/2011 or LN311/2006)

Red List 1989:

Not listed in the Red Data Book of the Maltese Islands

Poison:

Not Poisonous.

Herbaceous annual or biennial which is very common throughout the Maltese especially in Autumn/Winter. It consists of a green, erect stem with tiny white bristles, which forms many branches each giving rise to a terminal raceme of white flowers. The plant has a developepd taproot.

The basal and adult leaves are stalked and irregularly lobed. They have one or two pairs of basal leaf-lobes, cut deeply almost to the midrib, and a very large rounded terminal lobe. The shape of the young upper leaves is more or less maintained but they are usually sessile. Leaves have a crenated or shallow-dentate margin and prominent pinnate veins which normally have sparse tiny bristles.

The infloresences are racemes of many flowers of which 4 to 8 are found in blossom. The white flowers measure about 16-18mm across and consist of 4 narrow sepals, 4 white petals that slightly overlap each other and are arranged diagonally to each other (or cross-shaped), 6 stamens of which 4 are long and central, and 2 are short and lateral, and a central pistil with a superior ovary and swollen green stigma. The stamens produce yellow pollen.

When the flower expires, it drops its sepals, corolla and stamens leaving the ovary which elongates and forms a slender rod-shaped fruit called a siliqua. They are green (but can partially attain a purple-brown colour), have a body which is slightly bulging with the seeds inside, and an apical short beak. Mature pods measure between 25-38mm long and 2mm across and store around 40-80 seeds that are arranged in stacked pairs at each side of a central partition called replum. When mature, the fruit walls open with a sudden twist causing the seeds inside to scatter at a certain distance. The central translucent replum remains visible for some time. The seeds are ovoid (with a tiny indentation), yellow-brown, smooth, and about 1-2 mm accross.

Information, uses and other details

Allergy to Diplotaxis erucoides pollen:

Abstract from research by P. Garcia Ortega et al [304] about Allergy to Diplotaxis erucoides pollen: occupational sensitization and cross-reactivity with other common pollens " Background: Diplotaxis erucoides is a common weed of the Brassicaceae family widespread in southern and central Europe.

Methods: A total of 410 consecutive patients referred for allergy study of rhinoconjunctivitis and/or asthma were skin tested with D. erucoides pollen, 14 proving positive. A purified D. erucoides pollen extract was prepared to perform quantitative skin tests, provocation tests, immuno-blotting, and EIA inhibition in the 14 sensitized patients.

Results: Three patients, directly involved in viniculture, had rhinoconjunctivitis related to D. erucoides pollen. No D. erucoides-related symptoms were observed in most patients, who were also sensitized to Artemisia pollen. RAST was positive in 12/14 patients and nasal provocation tests in 9/12. The molecular masses of the most prevalent IgE-binding proteins ranged from 26 to 27.5 and from 31 to 34 kDa. D. erucoides pollen inhibited the IgE-binding of other sensitizing pollens in the three viniculture workers, whereas both Artemisia and D. erucoides pollen produced similar heterologous inhibition in the pooled serum of the remaining, nonclinically affected, D. erucoides-sensitized patients.

Conclusions: D. erucoides pollen may be an important prevalent aeroallergen, particularly in rural areas. It may act as an occupational allergen in vineyard workers, in whom it seems to be the primary sensitizing agent, playing a secondary cross-reactive role in other sensitized patients. "

Go in the links section to read full text document about this research

The seed is best sown in situ as soon as it is ripe, though it can also be sown in situ in the spring [KF]. The seed usually germinates in the autumn and survives as an over-wintering rosette [17]

Leaves can be eaten raw or cooked. They possess a mustard-like flavour, they can be added to salads [217].

No evidence of medicinal use was found [SM]

Personal observations

Dispersion
Dispersion of seeds is by sudden outwards twisting of the 2 outer walls (valves) forming the siliqua [SM]

The plant is abundant in November and December in Malta, and is responsible for the formation of white carpets of flowers, usually over an uncropped field during the months of November and early December. During these months, there are not many flowers in bloom, and so this makes this species to predominate. [SM]



Not much information about this plant has been found, neither in books nor on the internet. If you can supply further information to be included in this profile, please, do not hesitate to email me. Full reference credits will be given.

Photo Gallery   (48 Images)

IMAGE: DTXER-01

Photo of white flowers situated at the top of the flowering branches.

IMAGE: DTXER-02

Close-up photo of adult flowers which consists of 4 white petals arranged as the shape of a cross. Very rarely, specimens with pale violet flowers are seen (see image DTXER-05).

IMAGE: DTXER-03

Photo of a typical flower about 12-20mm across.

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Photo of several flowers at different maturities, crowding the top of the flowering branch.

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Photo of a young flower (pure white) and mature flower (with lilac/purple tinge) on the same specimen.

IMAGE: DTXER-06

Close up of flower having 6 stamens, 2 of which are short and lateral, and the remaining 4 are taller and arranged around the pistil.

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Another photo of the flowers of this species.

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Lateral view of flower highlighting the pistil surrounded by the stamens having yellow anthers and firm filaments.

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Close-up of a flower showing the arrangement of the 6 stamens around a central pistil at the centre of the flower. Young flowers have the pistil shorter from the stamens, and elongates with maturity.

IMAGE: DTXER-10

Photo of an inflorescence made up of racemes of 3 - 8 white blossoming flowers. Each flowering branch can produce up to 80 flowers which do not blossom together, but gradually from bottom to top - what is known as an indeterminate inflorescence.

IMAGE: DTXER-11

Close up photo of a flower (lateral view) showing the 6 stamens and a central pistil with a swollen stigma. The colour of the filaments is green in young flowers and becomes lilac-purple in older flowers.

IMAGE: DTXER-12

Photo of inflorescence made of a raceme of clustered white flowers at the top of the flowering branch, and progressively gets more lax and spaced down the stem when the flowers develops into fruit.

IMAGE: DTXER-13

Close up image of few young flowers.

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Photo of flowering branch with flowers and elongated fruit-pods known as silique (sing. siliqua).

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Scanned image of 2 flowers (one dissected laterally) against a dark background.

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Scanned and annotated image of flowers showing in detail their various flowering parts.

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Another photo of the four-petal, white flowers clustered at the top of the flowering branch.

IMAGE: DTXER-18

Scanned and annotated image of a longitudinally dissected flower (with some petals and sepals removed) showing the arrangement of the 6 stamens around the pistil.

IMAGE: DTXER-19

Photo of leaves of Diplotaxis erucoides which have 2-4(or up to 6) pairs of lateral lobes and a terminal lobe which is always the largest.

IMAGE: DTXER-20

Scanned image of an adult leaf. It has deep lobes at the base followed by an apical and terminal roundish large lobe. The margin is shallow dentate (or crenate).

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Photo of adult leaf with small lateral lobes and a larger terminal lobe.

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Photo of leaves at the upper part of the stem (just below the inflorescences). Such leaves are small, sessile and often unlobed (or with shallow lobes).

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Photo of adult(stem)leaves showing their lobed morphology.

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Scanned and annotated image of young and adult leaves. They are deeply lobed with the apical lobe being the largest and shortly.

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Top view photo of a plant. It is a herbaceous, multi-branched, annual plant with several flowering stems that are in full bloom in November-December.

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Photo of plant emerging from a carpet of the invasive Oxalis pes-caprae.

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Photo of young plant in leaves and developing buds.

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Photo of the upper plant of the plant which consists of numerous, spread-out siliqua and racemes of white flowers.

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Photo of a flowering branch.

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Photo of flowering branch taken in December. Inflorescence described as an indeterminate raceme.

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Photo of a specimen from a field in Qala (Gozo) on 23rd November 2013.

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Photo with strange morphology (growth distortion) caused by a fungal pathogen (Albuga candidans) which effects several species of the mustard family (Brassicaceae/Cruciferae).

IMAGE: DTXER-33

Scanned image of the upper part of the plant including a cauline leaf, several fruit pods and a raceme of white flowers at the apex.

IMAGE: DTXER-34

Scanned and annotated image of the flowering stem showing racemes of flowers at the upper part followed by plenty of long, spread-out, seed-bearing siliqua.

IMAGE: DTXER-35

Close up photo of the siliqua which is elongated and often reddish brown in colour. The beak (tip) is very short.

IMAGE: DTXER-36

Close up photo of another siliqua, an elongated fruiting pod with a central longitudinal partition dividing seeds into two rows.

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Scanned image of some siliqua at progressive maturity stages. The pods tend to be purple brown especially if they are exposed to the sun.

IMAGE: DTXER-38

Magnified scanned image of 3 fruit-pods. They have a long pedicel, a short beak and slightly bulging bodies with the seeds inside.

IMAGE: DTXER-39

Scanned image of ripe siliqua and their seeds. The walls (=valves) break open from the base and twist rapidly to disperse seeds some distance away.

IMAGE: DTXER-40

Magnified scanned image of 3 open siliqua. They have this characteristic translucent central partition (=replum) to which seeds are attached to. Each fruit-pod holds between 40 - 80 seeds each.

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Scanned image of the seeds. They are oval to sub-spherical in shape with a small indentation. They measure about 1.5mm in diameter and are light brown in colour.

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Scanned image of the subterranean parts - a developed tap-root and numerous outgrowing roots.

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Photo of plants with empty siliqua. The remaining translucent replum of the siliqua glistens bright against sunlight.

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Photo of a several plants in their natural habitat, which normally is deep fertile soil found for example in fallow fields, abandoned fields, disturbed soily areas, vine-yards, traffic islands and uncared gardens.

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Photo of an fallow field covered with white flowers of D. eurocoides (30/Oct/2005).

IMAGE: DTXER-46

Photo of a field covered with white D. erucoides and yellow Brassica rapa spp. sylvestris. Photo taken from Dingli cliffs on November 2004. It is quite common to find populations of these two species together in November/December.

IMAGE: DTXER-47

Photo of an fallow field covered with D. erucoides taken in fields at Qala, Gozo (Nov 2013).

IMAGE: DTXER-48